OK don't try just in order to (un)confirm, your system is likely to freeze completely and the hard reset be the only solution.

OK, google tells me that this has been occurring in ancient times but that the problem was fixed.
But here, I'm running rosegarden 13.04 under a 3.8.13 kernel and... the system completely freezes as soon as I select the hr timer as midi clock source.
(No trace available nowhere of course)

I was wondering if maybe Rosegarden's graphics settings were involved, but I saw no difference in this case between "fast" and "safe". But I did notice that there's some lag when starting JACK with ALSA (I normally start it with firewire). There was some delay on startup, and then a short freeze every time I highlighted a new track. So I'm wondering if ALSA is the real culprit here.

I was wondering if maybe Rosegarden's graphics settings were involved, but I saw no difference in this case between "fast" and "safe". But I did notice that there's some lag when starting JACK with ALSA (I normally start it with firewire). There was some delay on startup, and then a short freeze every time I highlighted a new track. So I'm wondering if ALSA is the real culprit here.

Hmmm... as far as I understand, you do not manage to reproduce my problem.
Could you please confirm that your implementation of rosegarden is actually using the hr-timer as midi clock source ? (Edit/configure/MIDI/Clock)

And... moreover, which clock source does your jackd implementation uses for midi ? And what did you select associated with the -X parameter in jackd ?
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EDIT : OK! Thank you, audiodef, for your help but you can stop your efforts as I have had some kind of answer on the rosegarden's mailing list.

In short : The problem is with the snd_hrtimer module. Either it works, or it freezes the system entirely at once and things have been so for the last 10 years._________________

There's an option to switch the timer from "auto" to your selected preference. If that's what you're referring to, perhaps you don't have the correct module loaded and that's why it freezes. The easiest way to know whether the module is loaded is to verify that your kernel is configured for it and to modprobe the module. Of course, if it's in your /etc/conf.d/modules, it should be loaded already. If it's compiled into the kernel, try configuring it as a loadable module instead. I've been told by devs that it shouldn't matter, but the practical reality is I've found some things more stable as loadable modules than compiled into the kernel._________________Gentoo Studio: http://gentoostudio.org
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